Currently, most apparatus used as human tactile input devices to control electronic systems, such as computers, use mechanical, electronic, optical, or some combination of these means to measure a force, velocity, or displacement that is converted to a parameter suitable for input to the system. The most common are mechanical or optically based and they typically control a cursor motion, an object selection, scrolling, or other operator input commands based upon visual feedback from a display device while the system under control is executing a function. Mouse devices, track-ball devices, joystick devices, and electrostatic position sensors are widely used. These apparatus, all capable of performing basic functions of an input device, each suffer from various deficiencies.
In the case of a mouse device under normal operation, whether mechanical or optically based tracking mechanisms are used, the device must be physically separated from other components of the electronic system and must be translated in physical contact to and across a relatively flat surface. Additionally, in the case of a computer, an operator must repeatedly reposition a hand between a keyboard and a mouse to perform alternately each device's control functions. Track-ball devices, joystick devices, and electrostatic sensors may be mounted on a keyboard or primary data entry device for an electronic system and thus do not necessarily require repetitive repositioning of an operator's hand. However, these devices are essentially two-dimensional control devices because they can only access two-dimensions simultaneously.
Furthermore, all the above-mentioned devices require physical contact between the operator and the control device, which causes mechanical wear. When these devices are mounted on a keyboard or other primary input device, they are usually required to take up a small amount of space. Because physical contact is required, operators' hand motions must also be small. If the controlled parameters on the machine must cover a large scale compared to the required resolution, control through small hand motions is very sensitive and uncomfortable.
More specifically, Nestler et al. U.S. Pat. No. 4,799,055 and Jackson U.S. Pat. No. 4,794,384 both disclose mouse devices which image light reflected from a two-dimensional surface onto a photo-detector array and analyze the output of the array to determine the direction of movement of the array. However, these devices are limited by the nature of the surface, the degrees of freedom of surface motion they can detect, and the need for mechanical interaction with the surface and the user's hand. The device in Snow U.S. Pat. No. 5,274,361 measures the dopler shift of light reflected from a surface as the device is moved across the surface, but otherwise has the same limitations as Nestler et al and Jackson. Another type of surface motion detection is disclosed in Klein et al. U.S. Pat. No. 6,008,887, wherein the interference pattern produced by vibration of an object illuminated by coherent light is translated into electrical signals by a photo-emf detector; however, Klein et al. is limited to detecting oscillation patterns representative of surface vibration characteristics of the object.
One non-contact and optically based input apparatus disclosed in Rangan, U.S. Pat. No. 5,999,166, although addressing many of the aforementioned deficiencies, requires a reflective element to be attached to the hand to redirect a light source in preferential directions in order to provide control. In general, the currently available human-machine input control devices typically possess at least one major deficiency: ergonomic inefficiency, the need for additional mechanisms to access a third dimension, the need for physical contact, inherent mechanical wear, or the need for hand attachments.